The present invention is concerned with a novel, safe, and efficient process for the preparation of known and novel nitroimidazoles and novel intermediates therefor. Also, the invention includes the selected novel nitroimidazoles. The nitroimidazoles both known and novel as well as novel intermediates are sensitizers for radio- or chemotherapy.
Known nitroimidazoles for use as sensitizers are found in U.S. Pat. No. 4,282,232 and various U.S. Pat. Nos. 4,581,368; 4,596,817; 4,631,289; and 4,757,148 claiming British priorities of Ser. Nos. 821,5545; and 8231107 (EP equivalent applications No. 83/303063.8) and are all aziridino-containing nitroimidazoles. Disclosed in U.S. Pat. No. 4,596,817 are nitroimidazoles of the general formula ##STR1## wherein R' is hydrogen or alkyl; n is 1 or 2; R'.sub.2 -R'.sub.5 are hydrogen, alkyl, aryl, aralkyl or alkaryl; and Y is halogen such as bromine or chlorine, shown as intermediates. These also are now found to exhibit activity as sensitizers.
The synthesis of the above-noted references is, for example, generally ##STR2## having the disadvantage of poor overall yield. Further, the above synthesis is disadvantageous because it requires the use of the highly toxic, known carcinogenic, ethyleneimine and possibly other highly toxic aziridines. It begins with 2-nitroimidazole and provides only limited analogous products through a highly unstable aziridine ring containing compound. Particularly, use of ethyleneimine above requires stringent compliance with safety regulations.
On the other hand, the present invention process uses various 2-oxazolidone analogs to provide a wide range of compounds for use as sensitizers having a nitroimidazole ring and is not available to an artisan in prior known references. Thus, the present process shows preparation of both known and novel compounds each having both the nitroimidazole and either 2-oxazolidinone substituents or derivatives of 2-oxazolidinone substituents.
Contrary to the previously known process shown above, the present process provides the desired product in higher yield with fewer process steps and gives products having a predetermined stereochemistry for the substituents noted below as R and R'. That is, in the opening of the aziridine ring in the old methods, a mixture of isomers resulted either which was not separated or for which separations were not readily accomplished, if at all.
Some 2-oxazolidone derivatives and selected processes for making such derivatives are known. For example, the 2-oxazolidone of Musser et al, J. of Med. Chem., p. 2092, Vol. 30, No. 11 (1987) includes a product cyclized from a compound having a phenyl. Kano et al, Tetrahydron Letters, pp. 6331-4, Vol. 28, No. 50 (1987); Evans et al, J. Am. Chem. Soc., pp. 2129-31, Vol. 103 (1981); and Ishizuku and Kunieda, Tetrahedron Letters, pp. 4185-8, Vol. 28, No. 36 (1987) discloses ring cleavage of an oxazolidone to obtain an amino alcohol. Kleschick et al, J. Org. Chem., pp. 3168-9, Vol. 52, No. 14 (1987) provides cyclization of a side chain attached to the 2-oxazolidone to provide a cyclopropyl containing compound from which the 2-oxazolidone is then removed. However, all of these references fail to teach the steps of the present invention.
Additionally, the presence of both a 2-oxazolidone and an imidazole is shown on an intermediate in the path of metabolism of Metoprolol in J. Med. Chem., pp. 55-9, Vol. 31, No. 1 (1988) and, further, a thiofuran having a cyclized amino alcohol side chain is disclosed as an anticancer agent in C.A. 102:6544 (1985). But again, the present invention is completely different from these disclosures.
Finally, the present invention is also the pharmaceutical compositions and methods of use for the novel nitroimidazoles described herein.